Sewing machine noise and vibration reduction

ABSTRACT

Noise and vibration are reduced in an axial cam drive mechanism radial spring loading the rotary cam assembly to one end of its limit of axial travel. The spring load is applied through an antifriction axial thrust bearing, and is reacted by a second antifriction radial thrust bearing. The spring load applied exceeds the axial component of the maximum reaction load applied by the cam driven mechanism during operation so that there is no tendency of the rotary cam assembly to shift axially upon reversal of the reaction load.

nite States tet H 1 H 1 3 Pierce May 28, 1974 [5 SEWING MACHINE NOISEAND 2,879,733 --3 1959 Pierce 112/256 VIBRATION REDUCTION 3,279,403/1966 Jarrett 112/218 R [75] Inventor: lgiiqnnard N. Pierce, WestHartford, Primary Examiner H Hampton Hunter Attorney, Agent, orFirmBrowne, Beveridge, De [73] Assignee: The Merl-0w Machine Company,Grandi & Kline Hartford, Conn.

[22] Filed: May 3, 1973 57 ABSTRACT [21] Appl. No.: 356,851 Noise andvibration are reduced in an axial cam drive mechanism by spring loadingthe rotary cam assembly 52 1. 11 218 R 74 567 1mm 2? The SPmg P l5 ll11.? 8 if we 65/02 is hhhhhh hhhhhhh hh hhhhhhhhh hhhhhl hhhhh hhhhhh,[58] Field of sgarch 112/220 218 R 221 and is reacted by a secondantifriction radial thrust 308/163 6 bearing. The spring load appliedexceeds the axial component of the maximum reaction load applied by [56]References Cited the cam driven mechanism during operation so that thereis no tendency of the rotary cam assembly to UNITED STATES PATENTS shiftaxially upon reversal of the reaction load. 1,349,157 8/1920 Kingsbury308/160 2,043,790 6/1936 Baker i. 308/163 6 Claims, 4 Drawing Figures 0x 66 68 l I2 a no 7 i 19.2 ivil M 42 14 1 genita r 1 SEWING MACHINENOISE AND VIBRATION REDUCTION BACKGROUND OF THE INVENTION DESCRIPTION OFTHE PRIOR ART In many types of modern machinery, axial cams are employedto drive working elements in a direction to impart a component ofmovement parallel to the axis of rotation of the drive cams. Thisproduces a reaction force tending to move the cam along its axis betweenthe limits of necessary running clearance established by restrainingbosses or bearing surfaces, resulting in the drive cam striking one ofthe opposed restraining bosses upon each reversal of the driven member.The repeated driving of the cam between its opposed axial stops producesobjectionable noise and vibration, par ticularly in high speed machinessuch as industrial sewing machines which require the continuous closeattendance of an operator.

While certain aspects of the invention may be appropriate for generalapplication, other features are particularly applicable to an overedgesewing machine of the well-known Merrow type illustrated, for example,in my prior U. S. Pat. 2,879,733. Accordingly, the invention will bedescribed herein with particular reference to such an overedge sewingmachine in which a shaft driven needle cooperates with a lower and anupper looper to form an overedge seam. The loopers are mounted on loopercarriers having cam followers thereon actuated by a pair of grooved camcylinders mounted for rotation about their longitudinal axes within themachines rigid frame. The cam cylinders are rigidly mounted on spacedparallel shafts which, in turn, are journalled for rotation in theframe, and the cylinders and their respective shafts are restrained,within the necessary limits of running clearance, against axial movementby opposed bearing surfaces within the frame which engage the radial endfaces on the respective cam cylinders. Although the mass of therespective cam cylinders and their associated shafts is substantiallygreater than the driven looper carriers and their associated drivencomponents, the reaction force produced by the looper carriers duringhigh speed operation of the machine is, nevertheless, sufficient todrive the cam cylinders in an axial direction back and forth in the mainframe to strike each of the restraining bosses upon each revolution ofthe cams. Assuming that the machine is being driven at a rate of 6,600rpm, the two cams, each hitting their opposed restraining bosses on eachrevolution, will produce 440 impacts per second. Thus it is apparentthat this slight axial movement of the relatively heavy axial camcylinders can be a major source of objectionable noise and vibration. Itis, accordingly, a primary object of the present invention to greatlyreduce or completely eliminate noise and vibration resulting from axialshifting of drive cam cylinders in an axial cam driven mechanism.

Another object of the invention is to provide an improved axial camdriven machine in which axial shifting LII of the driving cam cylindersis avoided without interferring with the necessary running clearancesrequired for high speed operation of the cam cylinders.

SUMMARY OF THE INVENTION In the attainment of the foregoing and otherobjects, an important feature of the present invention resides inproviding antifriction axial thrust bearings between the ends of theaxial cam cylinders and their opposed restraining bosses, and providinga resilient compression spring member between one of the axial thrustbearing assemblies and its adjacent restraining boss to spring load thecam cylinder and its associated shaft against the opposed restrainingboss. The spring force is maintained at a level exceeding that which maybe generated by the reaction of the elements driven by the cam so that,regardless of the reaction forces, there is no tendency for the cam toshift axially during operation of the machine as a result of thereaction forces. Since the spring force acts on the cam through theantifriction axial thrust bearing, this axial load on the cams haslittle, if any, effect on the power required to operate the mechanism.At the same time, the compression spring can readily be designed toaccommodate greater tolerances than were possible in the prior artdevices.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 3 is an enlarged fragmentarysectional view of one end of the lower cam cylinder shown in FIG. 1; and

FIG. 4 is an enlarged fragmentary sectional view of the opposite end ofthe cam cylinder shown in FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings indetail, a cam driven overedge sewing machine embodying the presentinvention is indicated generally in FIG. 1 by the reference numeral 10,and includes a main casting 12 having a mechanism compartment 14 and anoil reservoir compartment 16, with the mechanism compartment and oilreservoir being separated by a partition 18 extending between the frontand back walls of the machine. An end wall 20 formed as an integral partof the frame 12 and extending substantially parallel to the partition 18cooperates with a base plate 22 and top wall portion 24 to complete theenclosure for the mechanism compartment 14.

A main or lower drive shaft 26 extends through the frame 12 and isjournalled for rotation by suitable bearings such as the bushing 28,needle bearing 30 and the inner bearing surface of bore 31. A combinedV-belt drive pulley and hand wheel 32 is mounted on the end of shaft 26projecting outwardly from the frame 12.

A second or auxiliary shaft 34 is mounted in frame 12 for rotation aboutits longitudinal axis which extends parallel to the axis of shaft 26.Auxiliary shaft 34 is journalled for rotation by a bearing 36 machinedat the end wall and a second plain bearing 38 defined by a bore 40extending through the partition 18 to the end of the machine frame 12. Ascrew plug 42 normally closes the end of the bore 40. A lower camcylinder 44 is rigidly mounted, as by set screws, not shown, on the mainshaft 26 within the mechanism compartment 14, and a second cam cylinder46 is similarly mounted on the auxiliary shaft 34. As seen in FIG. 2,lower cam cylinder 44 has a pair of cam grooves 45, 47 and a spur gear48 formed on its cylindrical surface. The upper cam cylinder 46 has acam groove 49 and a similar spur gear 50 on its outer surface, withgears 48, 50 meshing so that rotation of the lower cam cylinder 44 bythe main drive shaft 26 will also drive the upper cam cylinder 46 andits associated auxiliary drive shaft 34.

Partition wall 18 has integrally formed thereon a pair of outwardlyprotruding thrust bearing surfaces, or bosses 52, 54, with the thrustbearing surface 52 surrounding the lower shaft 26 and extending inparallel opposed relation to the right end surface 56, as viewed fromthe front of the machine, of the lower cam cylinder 44. Similarly,thrust bearing surface 54 surrounds the auxiliary shaft 34 and extendsin parallel opposed relation to the right end surface 58 of upper camcylinder 46. A third thrust bearing surface, or boss 60 is formed on theend wall 20 in parallel opposed relation to thrust bearing surface 52,and extending in parallel opposed relation to the left end face of thelower cam cylinder 44. Thus, thrust bearing surfaces 52, 54 restrainmovement of the cam cylinders 44, 46, and their associated shafts, inthe right-hand direction as viewed in FIG. 1, while thrust bearingsurface 60 limits movement of the lower cam cylinder to the left.

Movement of the upper cam cylinder to the left, again as viewed in FIG.1, is restricted by an upper cam thrust bracket 64 mounted by aligningpin 66 and screw 68 extending into the top wall 24. The cam thrustbracket 64 includes a downwardly projecting cantilevered arm 70 having acircular aperture 72 formed therein for receiving the auxiliary shaft34, with a thrust bearing surface 74 extending in opposed parallelrelation'to the left end face 76 of the upper cam cylinder 46. In theunstressed condition, the bearing surface 74 is inclined at a slightangle with respect to the longitudinal axis of the auxiliary shaft 34 sothat, when a load is applied parallel to the axis of the auxiliaryshaft, the surface 74 will assume an attitude perpendicular to the shaftand parallel to the thrust bearing surface 54.

Endless cam tracks 45, 47, 49 extending around and into the outerperiphery of cylinders 44, 46 normally engage cam followers, not shown,on the machines upper and lower looper carriers in the mannerillustrated in my above-mentioned patent, the disclosure of which isincorporated herein by reference for purposes of illustrating theoperation of the loopers and related mechanisms as well as the primarylubrication and sealing systems of the machine.

As is well-known, the reaction force applied to the cam cylinders 44, 46by the cam followers running in the cam tracks tends to shift the camcylinders and their associated shafts in an axial direction between theopposed thrust bearing surfaces disposed at the opposed ends of therespective cam cylinders. Although extreme care is exercised inproduction of the equipment, some finite running clearance is requiredto avoid excess friction and wear and to avoid binding due to heatdifferentials, or the like. In the prior art machines of the typeillustrated in my aforementioned patent, this running clearance wasnormally maintained at a maximum of 2 mils, and the cam cylinders werethus subject to being driven back and forth between the opposedcontining thrust bearings on the frame, within these limits, upon everyrevolution of the respective cam cylinders by the reaction forces of thecam followers and their associated driven components.

To overcome this tendency of the cam cylinders to be shifted back andforth, and to eliminate any noise and vibration generated thereby,according to the present invention, the respective cam cylinders areprovided with a spring loaded antifriction thrust bearing system whichspring loads the cam cylinders to one end with an axial force whichexceeds the maximum axial component of the reaction force applied by thecam followers during normal operation of the machine. Since the springloaded thrust bearing system of the respective cam followers aresubstantially identical, only the system for the lower cam cylinder 44will be described in detail herein, it being understood that thedescription applies equally to the system for the upper cam cylinder 46.Further, identical reference numerals will be applied to identifycorresponding elements of the spring-loaded thrust bearing system of thecam cylinders 44 and 46.

Referring now to FIGS. 2 and 3, it is seen that cam cylinder 44 has aconcentric counterbore 80 formed in its left end and terminating in aradial face 82 spaced inwardly from and parallel to the end face 62. Theradial face 82 is carefully machined to form the inner race of an radialthrust bearing assembly which includes a plurality of radially extendingrollers 84 spaced by a suitable bearing retainer 86 and an outer racedefined by a relatively thick annular washer 88. A pair of similarcorrugated spring washers 90 are positioned within the bore 80 and bearagainst the outwardly directed face of the outer race 88, and a secondrelatively heavy metal washer 92 bears against the outer face of thespring washers. The dimension of the rollers 84, the outer race 88, thespring washers 90, and the metal washer 92 is such that their combinedthickness is slightly greater than the depth of the counterbore 80 sothat the outer surface of the washer 92 normally bears against thethrust boss 60 to maintain the radial face 62 of the cam cylinder 44spaced therefrom a slight distance. Since the spring washers 90 are insurface-tosurface contact with the outer race 88 and the metal washer92, the race 88 and spring washers 90 are stationary during operation ofthe machine.

Referring now to FIG. 4, it is seen that a second concentric counterbore94 is formed in the right end of cam cylinder 44, with the counterboreterminating in a radial face 96 defining the inner race of a secondaxial thrust bearing assembly. The second thrust bearing assemblyincludes a bearing retainer 98 which holds a plurality of radiallydisposed rollers 100 and an annular spacer 102 having a radial innerface defining the outer race of the bearing. The spacer 102 has athickness, or axial dimension which, combined with the diameter of therollers 100, is slightly greater than the depth of the counterbore 94 sothat the radial end face 56 of the cam cylinder 44 is retained inclosely spaced relation to the thrust bearing surface 52.

When the axial thrust bearing assemblies are assembled into the opposedends of the cam cylinder 44, their overall axial dimension is slightlygreater than the space between the opposed thrust bearing surfaces 52,60 so that the spring washers 90 must be compressed to position theoverall assembly between these thrust bosses. In this condition, thespring washers 90 exert an axial force against the outer race 88 whichforces the cam cylinder toward the partition wall 18 to retain thespacer 102 into firm contact with the thrust bearing surface 52. Theforce exerted by the spring washers 90 is greater than that generated bythe reaction of the looper carrier cam followers so that, duringoperation of the machine, there is no axial movement of the cam cylinderand shaft.

By selection of spring washers 90 having the proper spring constant, therequired axial load can be applied to the cam cylinder without applyingexcessive load to the axial thrust bearings while still permitting sometolerance in the spacing between the opposed thrust bosses 52, 60.Further, since the end faces 56, 62 are no longer critcal bearing faces,the dimensional tolerances and surface finishes of these faces are nolonger as critical as in the prior art machines.

To supply lubricating oil to the axial thrust bearing assemblies on theupper cam cylinder 46, a spiral groove 106 is formed on the outersurface of the auxiliary shaft 34, with the groove extending from aposition communicating with the normally pressurized vertical oilchannel 108 of the machines pressure lubricating system. The spiralgroove 106 extends past the inner race 96 and is formed to propellubricating oil from the channel 108 axially along the shaft tolubricate the bearing 38, with the excess lubricating oil being carriedinto the thrust bearing assembly. To allow the oil conveying groove 109to impel oil through spacer member 102 more freely, the axial bore ofthe spacer member has a plurality of axially extending grooves 109formed around its inner periphery.

Excess oil supplied into the counterbore 94 will be thrown bycentrifugal force toward the outer cylindrical surface of thecounterbore and a portion thereof will flow into the longitudinallyextending, diverging oil channel 110 to be conveyed by centrifugal forceaxially through the cam cylinder 46 and discharged into the counterbore80 at the left end of the cam cylinder to lubricate the left-hand axialthrust bearing assembly. A portion of the oil passing through channel110 is thrown centrifugally through an aperture 112 to lubricate the camtrack 49 and the cam follower disposed therein. A loose metering rod 114disposed within the channel 110 assures that a portion of the oilflowing through the channel will be conveyed past the radial hole 112 tolubricate the thrust bearing assembly. Also, it is pointed out that thespacer 102, the outer race 88, and washer 92 have outside diametersslightly less than the diameter of the counterbores within which theyare received so that excess lubricating oil can flow axially therepastand be discharged into the mechanism compartment 14.

The spacer 102 has an outer peripheral surface which is slightlycone-shaped so that excess lubricating oil which flows by gravity aroundthe periphery of this spacer, or outer race and collecting at the bottomof the counterbore 94 will then tend to flow, by gravity and capillaryaction along the inwardly and downwardly inclined coneshaped outersurface of the spacer into the counterbore 94. This tendency for the oilto flow inward into the counterbore further assures a continuous supplyof lubricating oil in addition to that supplied by the spiral groove106.

A similar araangement is employed to supply lubrication oil to the axialthrust bearings of the lower cam cylinder. Thus, the spiral groove 116conveys lubricating oil from the channel 108 into the counterbore 94 inthe same manner as with the bearings on the upper cam 46. Excesslubricating oil flows from the counterbore into two axially extending,outwardly diverging channels 118, 120 to supply lubricating oil to camfollowers positioned within cam grooves 45, 47, respectively, and tosupply lubricating oil to the thrust bearings at the left end of the camcylinder 44. Metering rods 122, 124 are positioned within the channels118, 120, respectively and a radially extending opening 126 in thechannel 118 supplies lubrication to the cam track 45 and the camfollower disposed therein. A similar radially extending opening 128permits a portion of the lubricating oil flowing in channel 120 toescape to lubricate the cam track 47 and the cam follower disposedtherein. with the metering rod 124 conveying the remainder of the oilpast the opening 128 to be discharged into the counterbore 80 tolubricate the axial thrust bearing at the left end of the cam cylinder44.

As seen in H6. 1, the main shaft 26 has an axially extending bore 130formed therein from its right-hand, or drive end and terminatingadjacent the left end. A radially extending opening 132 formed in theshaft from the trailing edge of the machine's oil scavenge pumpeccentric 134 provides a fluid passage admitting a portion of thelubricating oil pumped by the scavenge pump to flow into the axial bore130 of shaft 26. Metering and conducting rods 138, 141 are positionedwithin bore 130 and radially extending opening supplies additionallubricant to the axial thrust bearing at the left end of cam cylinder44. Screw 142 is provided near the right end of bore 130 to retainmetering and conducting rods 138, 141 and to seal bore 130 so that allof the lubricant therein is directed to opening 140 and cannot escapethrough opening 136 to contaminate the V-belt drive groove in drivepulley 32. Screw 143 is provided at the extreme right hand end of bore130 as a safety precaution and to permit convenient use of certain typesof tachometers in measuring the speed of the sewing machine. Thus, theaxial thrust bearings are continuously supplied with an excess oflubricating oil to always assure adequate lubrication of the high speedbearings.

From the above, it is apparent that the vibration and noise resultingfrom repeated impacts between the main cams and the restraining bosseson the frame have been eliminated by preloading the cams into continuouscontact with one thrust bearing on the frame. By applying the preload tothe cam through an axial antifriction bearing, and providing an axialantifriction thrust bearing at the opposite end of the cam, the repeatedimpacts and associated noise are eliminated without adversely effectingthe operation of the machine. 7

While 1 have disclosed and described a preferred embodiment of myinvention, 1 wish it understood that 1 do not intend to be restrictedsolely thereto, but that 1 do intend to include all embodiments thereofwhich would be apparent to one skilled in the art and which come withinthe spirit and scope of my invention.

What is claimed is:

1. in a sewing machine having a frame, a cam cylinder mounted withinsaid frame for rotation about a longitudinal axis, a pair of oppositelydirected radial shoulders on said cam cylinder, a pair of bearingsurfaces on said frame, said shoulders being disposed in opposedrelation one to each of said pair of bearing surfaces for restrictingaxial movement of said cam cylinder about said longitudinal axis, anendless cam track formed on and extending around the outer surface ofsaid cam cylinder for engaging and driving a cam follower in a directionhaving a component extending parallel to said longitudinal axis wherebysaid cam follower applies a reaction force tending to move said camcylinder axially between said opposed bearing surfaces upon rotation ofsaid cam cylinder, the improvement comprising, a pair of antifrictionaxial thrust bearing assemblies mounted one between each said radialshoulder and the adjacent bearing surface, and spring means mountedbetween one of said axial thrust bearing assemblies and the bearingsurface adjacent thereto, said spring means continuously urging said oneaxial bearing and the cam cylinder toward the other of said axialbearing assemblies with a force greater than said reaction force appliedby said cam follower.

2. In a sewing machine as defined in claim 1, the further improvementwherein said spring means comprises at least one spring washer mountedbetween said one axial thrust bearing assembly and the radiallyextending bearing surface adjacent thereto, said spring washer beingcompressed upon assembly of the mechanism to apply a continuous axialload to said one axial thrust bearing.

3. In a sewing machine as defined in claim 2 the further improvementwherein said one axial thrust bearing assembly comprises a plurality ofradially extending antifriction rollers disposed between an inner raceintegrally formed on an end surface of said cam cylinder and an outerrace, and wherein said spring washer applies an axial force to andnormally restrains said outer race against rotation.

4. In a sewing machine as defined in claim 2, the further improvementwherein said axial thrust bearing assemblies each comprise a pluralityof radially extending antifriction rollers disposed between an innerrace inlegrally formed on an end surface of said cam cylinder means andan outer race, and wherein said spring washer applies an axial force toand normally restrains the outer race of said one thrust bearingassembly against rotation.

5. The sewing machine as defined in claim 4 wherein said oppositelydirected radial shoulders on said cam cylinder comprises the endsurfaces of said cam cylinder, and wherein said cam track comprises agroove formed in the outer surface of said cam cylinder.

6. in a sewing machine having a frame, a pair of cam cylinders mountedwithin said frame for rotation about spaced parallel axes betweenopposed bearing surfaces and having their ends positioned one closelyadjacent said bearing surfaces for restricting axial movement of saidcam cylinders along their respective axis of rotation, an endless camtrack formed on and extending around the outer peripherial surfaces ofeach said cam cylinder for engaging and driving a looper carrier camfollower in a direction having a component extending axially of saidcylinders whereby said looper carrier cam follower applies a reactionforce tending to move said cam cylinders axially between said opposedbearing surfaces upon rotation of said cam cylinders, the improvementcomprising axial thrust bearing assemblies mounted one between each endof each said cam cylinder and the adjacent bearing surface, andcompression spring means mounted between said axial thrust bearingassembly at one end of each said cam cylinder and the bearing surfaceadjacent thereto, said spring means continuously urging said axialbearings at said one end of said cam cylinders and the cam cylindersadjacent thereto toward the other of said axial thrust bearingassemblies with a force greater than said reaction force applied by saidlooper carrier cam follower.

1. In a sewing machine having a frame, a cam cylinder mounted withinsaid frame for rotation about a longitudinal axis, a pair of oppositelydirected radial shoulders on said cam cylinder, a pair of bearingsurfaces on said frame, said shoulders being disposed in opposedrelation one to each of said pair of bearing surfaces for restrictingaxial movement of said cam cylinder about said longitudinal axis, anendless cam track formed on and extending around the outer surface ofsaid cam cylinder for engaging and driving a cam follower in a directionhaving a component extending parallel to said longitudinal axis wherebysaid cam follower applies a reaction force tending to move said camcylinder axially between said opposed bearing surfaces upon rotation ofsaid cam cylinder, the improvement comprising, a pair of antifrictionaxial thrust bearing assemblies mounted one between each said radialshoulder and the adjacent bearing surface, and spring means mountedbetween one of said axial thrust bearing assemblies and the bearingsurface adjacent thereto, said spring means continuously urging said oneaxial bearing and the cam cylinder toward the other of said axialbearing assemblies with a force greater than said reaction force appliedby said cam follower.
 2. In a sewing machine as defined in claim 1, thefurther improvement wherein said spring means comprises at least onespring washer mounted between said one axial thrust bearing assembly andthe radially extending bearing surface adjacent thereto, said springwasher being compressed upon assembly of the mechanism to apply acontinuous axial load to said one axial thrust bearing.
 3. In a sewingmachine as defined in claim 2 the further improvement wherein said oneaxial thrust bearing assembly comprises a plurality of radiallyextending antifriction rollers disposed between an inner race integrallyformed on an end surface of said cam cylinder and an outer race, andwherein said spring washer applies an axial force to and normallyrestrains said outer race against rotation.
 4. In a sewing machine asdefined in claim 2, the further improvement wherein said axial thrustbearing assemblies each comprise a plurality of radially extendingantifriction rollers disposed between an inner race integrally formed onan end surface of said cam cylinder means and an outer race, and whereinsaid sprinG washer applies an axial force to and normally restrains theouter race of said one thrust bearing assembly against rotation.
 5. Thesewing machine as defined in claim 4 wherein said oppositely directedradial shoulders on said cam cylinder comprises the end surfaces of saidcam cylinder, and wherein said cam track comprises a groove formed inthe outer surface of said cam cylinder.
 6. In a sewing machine having aframe, a pair of cam cylinders mounted within said frame for rotationabout spaced parallel axes between opposed bearing surfaces and havingtheir ends positioned one closely adjacent said bearing surfaces forrestricting axial movement of said cam cylinders along their respectiveaxis of rotation, an endless cam track formed on and extending aroundthe outer peripherial surfaces of each said cam cylinder for engagingand driving a looper carrier cam follower in a direction having acomponent extending axially of said cylinders whereby said loopercarrier cam follower applies a reaction force tending to move said camcylinders axially between said opposed bearing surfaces upon rotation ofsaid cam cylinders, the improvement comprising axial thrust bearingassemblies mounted one between each end of each said cam cylinder andthe adjacent bearing surface, and compression spring means mountedbetween said axial thrust bearing assembly at one end of each said camcylinder and the bearing surface adjacent thereto, said spring meanscontinuously urging said axial bearings at said one end of said camcylinders and the cam cylinders adjacent thereto toward the other ofsaid axial thrust bearing assemblies with a force greater than saidreaction force applied by said looper carrier cam follower.